Self-Assembled\n8‑Ti-Containing Polyoxomolybdate\nfor the Photocatalytic Hydrogen Evolution

An S-shaped 8-Ti-containing polyoxomolybdate (NH<sub>4</sub>)Cs<sub>2</sub>Na<sub>6</sub>H<sub>3</sub>[Ti<sub>8</sub>(GeMo<sub>9</sub>O<sub>34</sub>)<sub>2</sub>(GeMo<sub>5</sub>O<sub>23</sub>)<sub>2</sub>]·44H<sub>2</sub>O (<b>1</b>) has been prepared\nunder\nthe one-pot hydrothermal method and further characterized. According\nto single-crystal X-ray, compound <b>1</b> consists of two {GeMo<sub>9</sub>O<sub>34</sub>} and two {GeMo<sub>5</sub>O<sub>23</sub>} segments,\nwhich are linked with a {Ti<sub>8</sub>O<sub>34</sub>} cluster. Moreover,\nthe {GeMo<sub>5</sub>O<sub>23</sub>} fragment is rare and the first\ndiscovery, which enriches the lacunary Keggin-type family and offers\nthe possibility of obtaining new structures. Among all of the reported\npolyoxomolybdates, compound <b>1</b> has the highest nuclearity\nof Ti centers. From the photocatalytic hydrogen evolution studies,\ncompound <b>1</b> can be used as the heterogeneous catalyst\nwith an H<sub>2</sub> evolution rate of 2392.6 μmol g<sup>–1</sup> h<sup>–1</sup> under minimally optimized conditions.